Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones).
While input devices have found many applications, engineers continue to seek design alternatives that reduce costs and/or improve sensor performance. For example, improvements in efficiently and reliably detecting and locating the presence of input objects in the sensing region.
One continuing issue is the ability to accurately track the position of input objects in the sensing region. In general, the greater the ability to accurately track object position the greater the usability of the device. This is particularly true for input devices that can sense and track multiple input objects simultaneously.
One particular area where the ability to track input objects is problematic is when one or more of these objects becomes occluded. In general, an input object is occluded when the sensor device is unable to fully determine or distinguish the input object. This may occur when an input object is not fully within the sensing region or when the input object is blocked by some nearby object or feature. In any case, the occlusion of the input object may result in the diminished ability to accurately track the position of the object as it moves in the sensing region.
Thus, there remains a continuing need for improvements in the techniques used to detect and identify objects in proximity sensor devices. Other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.